This invention relates generally to food packages and more particularly to expandable food packages constructed of non-metallic materials for use in a microwave oven.
Many expandable food packages have been contructed for use, for example, in packaging and cooking corn kernels for popcorn. Generally, the package is placed over a heat source under the influence of which cooking fats or oils, placed in the package, melt and form a gas while simultaneously the corn kernels are cooked to form popcorn, the combination causing the package to expand. Prior packages generally utilize a shallow metallic container for holding the food to be cooked covered by a thin foil cover. The cover expands under the influence of internal pressure from the cooked food to provide an internal volume greater than three times the original size.
A principle advantage of using an expandable package in which cooking can be preformed is the resulting economy of space in the storing and stacking of the packages. Another advantage is the convenience for the user of not having to transfer or handle the cooking ingredients stored in the package.
Unfortunately, packages incorporating metals cannot be used in a microwave oven because the metal acts as a shield thereby preventing the energy from reaching the food. Thus the food cannot be heated and cooked. As a result, it is necessary to design an expandable food package which is entirely non-metallic.
It is therefore an object of the invention to provide a non-metallic expandable food package for use in a microwave oven which is capable of expanding to at least three times its storage or unexpanded volume. Further objects of the invention are to provide a non-metallic, expandable food package which is inexpensive, simple to construct, easy to stack, will contain hot oils and cooking fats without leaking, is resistant to grease, is sanitary, and which, when expanded, will be selfsupporting. It is a still further object of the invention to provide a non-metallic, expandable food package which can be dispensed from a vending machine, which is easy to open, and which can be used as a bowl after cooking.